Preparation and characterization of silicate gel glasses containing Cr2O3 |
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Authors: | M. G. Ferreira Da Silva J. M. Fernàndez Navarro |
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Affiliation: | (1) Departamento de Engenharia Cerâmica e do Vidro, Universidadede Aveiro, 3800 Aveiro, Spain;(2) Instituto de Ceràmica y Vidrio, Arganda del Rey, Madrid, Spain |
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Abstract: | The effect of thermal treatment on the structural incorporation of Cr2O3 in xCr2O3·(100 – x)SiO2 and 5RnO·xCr2O3·(95 – x)SiO2 (where x=0.01–1 mol.% and R=Li, Na and Ca) gel glasses was studied by optical absorption spectrophotometry, DTA-TG, XRD and electron microscopy.Samples heat treated at 60°C have green color due to the presence of Cr3+ in octahedral coordination. The optical transmission, and color (yellow, orange or ambar), of the samples heat treated between 200 and 700°C prove that Cr3+ (octahedrally coordinated) and Cr6+ (tetrahedrally coordinated) are both present. Segregation of Cr2O3 take place at temperatures above 800°C.In reducing conditions the gel glasses were green due to the presence of a high content of Cr3+ ions. Samples containing Li or Na show crystalline phases at temperatures below 850°C. |
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Keywords: | color silica glass sol-gel |
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